1. Field of the Invention
The present invention relates generally to aerial message and display means using visible vapor distributed from one or more aircraft (e. g., "skywriting"), and more specifically to a system wherein a plurality of aircraft fly in formation, with each aircraft producing a relatively short puff of vapor controlled by a computer in a master aircraft. The master aircraft transmits an appropriate signal to a receiver in each of the other aircraft, according to the message to be displayed. A specially adapted interface and encoder device is placed between the computer and the transmitter in the master aircraft, enabling the computer to communicate with the transmitter in the same manner used in controlling a dot matrix printer.
2. Description of the Prior Art
The concept of "skywriting," i. e., maneuvering a single aircraft to produce one or more words using a visible vapor emanating from the engine exhaust or other source, has been known since shortly after the development of the first practical powered aircraft. Such displays always attract attention, as a pattern of smoke or vapor which forms words or designs in the sky is most unusual, and its location enables it to be seen for miles.
The basic concept utilizes only a single aircraft to produce one or more words or designs, which leads to several problems. First, any skywriting procedure requires that the aircraft fly relatively high (generally on the order of two miles above the surface), to avoid turbulent air at lower altitudes which would quickly break up any message or display, most likely before its completion. This leads to a second problem, in that the single aircraft must produce the entire message, a relatively slow procedure in which the first portion of the message often dissipates before the message is completed, even in stable air. A third problem with this technique is that the single aircraft must produce a prodigious amount of vapor or smoke, in order for the strokes formed to be seen clearly from such a high altitude. This leads to rapid depletion of the supply of oil or other material carried in the aircraft and used to produce the vapor or smoke.
Accordingly, as radio technology advanced, a system was devised wherein a single master aircraft would carry a transmitter and a program to transmit the message, with several receiving aircraft carrying receivers each receiving a discrete signal from the master aircraft to cause each receiving aircraft to produce a pulse of smoke or vapor automatically at the proper time. By flying the aircraft in a proper formation, each aircraft can simultaneously produce a portion of a message, thereby enabling the entire message to be completed much more quickly than by a single aircraft to reduce the effects of dissipation of the message and also allowing each aircraft to carry a smaller supply of vapor producing oil.
This basic concept of using several aircraft in formation is known as "Skytyping" .TM.. However, it is not widely used, as it also has certain disadvantages. For one thing, the transmission and reception system used, along with the message program, results in the individual message units or "smoke puffs" being produced in real time. This requires the aircraft to fly in a line abreast formation, i. e., spread laterally across the flight path. This type of formation flying is most difficult to perform, as each of the following pilots must focus and maintain their entire concentration upon the lead aircraft, ninety degrees to the direction of flight. Each pilot must have his/her head and neck turned in the direction of the lead aircraft during at least the entire message writing portion of the flight. This is not only tiring, but somewhat hazardous, as the aircraft are spread laterally on the order of two hundred feet apart, resulting in a spread of on the order of eight hundred feet between the aircraft at the extreme ends of the formation. With the pilots' attention being diverted from the direction of flight, the possibility of midair collision is relatively high.
The present invention overcomes these difficulties with a system which allows the aircraft to fly in a V or other formation, by adjusting the time for the transmission of the message signals according to the position of the individual aircraft in the formation. A discussion of the prior art known to the present inventor, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 1,426,413 issued on Aug. 22, 1922 to John C. Savage describes an Aerial Craft including a pair of tanks or hoppers each containing a substance which, when mixed together, will produce a visible vapor or smoke. The materials may be injected into the exhaust of the aircraft for distribution and further effect. Savage states that the use of a single material did not produce a sufficiently dense cloud of smoke, but the injection of a single material (i. e., oil) into the aircraft exhaust is commonly used today for such purposes. Savage is silent regarding the use of multiple aircraft in formation to produce an aerial message with the vapor output being controlled by a single aircraft in the formation, as provided by the present invention.
U.S. Pat. No. 1,850,635 issued on Mar. 22, 1932 to Willard Reed, Jr. describes a Method Of Forming Designs In The Sky. Reed, Jr. recognizes the difficulty in forming a legible word using a single aircraft, and the problems inherent in the use of one aircraft for such skywriting. Reed, Jr. thus uses a plurality of aircraft, each of which forms a single letter or a portion of a letter, in accordance with a predetermined pattern depending upon the specific word(s) or design(s) to be formed. The Reed, Jr. method differs from the present invention in that no communication is disclosed between aircraft or pilots while the aircraft are in flight, as provided by the present invention. The Reed, Jr. technique, while theoretically workable, is also potentially quite hazardous, with the aircraft involved crossing each others' flight paths several times during the forming of a single word or design.
U.S. Pat. No. 1,986,942 issued on Jan. 8, 1935 to John T. Remey describes an Apparatus For Sky Writing, comprising a perforated message sheet passing over a perforated track bar. The bar communicates pneumatically or optically with a series of relays activated when specific sheet and bar perforations are momentarily aligned as the sheet scrolls across the bar. The pneumatic portion of the system is similar to that used in the operation of a player piano or band organ. The relays each operate a valve, which emits a puff of smoke or vapor. The valves are all installed on a single tube trailed downwardly below a single aircraft in flight. Remey is silent regarding the use of multiple aircraft, or any means of display message communication between multiple aircraft.
U.S. Pat. No. 2,345,152 issued on Mar. 28, 1944 to John T. Remey describes Sky Writing With A Plurality Of Airplanes, wherein several slave aircraft each have a receiver which in turn selectively operates a smoke or vapor valve in that aircraft when a signal is received. Alternatively, the master signals may be transmitted by an aircraft in the formation, or by a transmitter on the ground, and the signal may be direct or may be an audio or visual signal to an operator in the aircraft. The automatic reception of transmitted signals by a master aircraft in the formation is loosely similar to the general procedure used in the present invention and is the foundation of the present "Skytyping" .TM. technique, but Remey provides no delay means to allow any other type of formation than line abreast or a single echelon, which would result in a swept or italicized font for the message.
U.S. Pat. No. 2,674,820 issued on Apr. 13, 1954 to Rolf K. Hansen et al. describes the Production Of Smoke Signs In The Air. The system uses a plurality of identical perforated panels, but each panel is modified according to the position of the aircraft to use that panel, within the aircraft formation. This allows the master aircraft to transmit unmodulated signals using only a single frequency, with each of the slave aircraft receiving identical signals to advance the message panels identically. However, since each of the panels is modified according to the position of the aircraft carrying that panel, those aircraft having panel positions which have been blocked out at any specific point will not produce a smoke puff at that radio transmission. While the present invention may make use of a single radio frequency, the modulation of that frequency allows only the master aircraft to carry the message means, with the slave aircraft each having only a receiver and smoke generating means. This allows any aircraft using the present invention to transfer to any part of the formation, by switching the specific modulated signal received by the aircraft to receive a signal appropriate to another point in the formation. The transmitting aircraft does not alter the transmitted signal in any way for this change. This is advantageous in that some portions of Roman letters (e. g., top and bottom strokes) require more oil vapor than other portions. Thus, the present invention allows aircraft to change positions, so aircraft using more oil may switch with those using less oil, to prolong the flight and messages formed.
U.S. Pat. No. 3,151,410 issued on Oct. 6, 1964 to Anthony Stinis describes a Sky Writing Apparatus wherein a master aircraft carries at least one message scroll and transmitter, with each slave aircraft having a receiver tuned to receive only a single one of the transmitted frequencies (or specific modulations of a single frequency) of the master aircraft. This system differs from the Hansen et al. system discussed immediately above, in that Hansen et al. functions more like a synchronizing signal for the messages carried in each of the aircraft, rather than actually transmitting the message, as is done by Stinis and also in the present invention. However, Stinis provides no means for different aircraft to change relative positions in the formation during flight, as provided by the present invention. Stinis does not provide any alteration of the message unit transmissions from real time, thus requiring all aircraft to fly in a line abreast formation, unlike the present invention. Stinis provides for up to two different messages to be formed in a single flight. The present system is also capable of being used to form multiple messages in a single flight, and in fact can form any number of different messages, limited only by the amount of smoke or vapor producing agent aboard each aircraft.
U.S. Pat. No. 4,561,201 issued on Dec. 31, 1985 to George A. Sanborn describes a Method And Apparatus For Sky Typing, comprising a string of vapor producing canisters which are trailed below a single aircraft. Sanborn mentions a computer, but provides no specific information or disclosure of the hardware and programming.
Finally, British Patent Publication No. 2,191,319 published on Dec. 9, 1987 to David J. G. Martin describes A Sky Graphics System, wherein a single aircraft carries a manifold having a plurality of nozzles for the dispersion of visible vapor therefrom. Each nozzle is controlled by an electronic valve, with a portable computer controlling the apparatus. No preferred method of carrying out the invention, or reduction to practice, is disclosed in the British publication.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.